Thomas p



(No Model.)

- T. ROWLAND. DOOR FOR DIGESTERS.

June 30, 1885..

N. PETERS. Phcldwutlwllipher. Wilhingtorb D. C.

UNITED STATES PATENT OFFICE.

THOMAS F. ROWLAND, OF NEW YORK, N. Y.

DOOR FOR ZDIGESTERS.

SPECIFICATION forming part of Letters Patent No. 320,971, dated June 30,1885.

' Application filed May 12, 1884. (No model.)

To all whom it may concern.-

Be it known that I, THOMAS F. ROWLAND, of the city, county, and State ofNew York, have invented certain new and useful Improvements in Doors forDigesters and Similar Structures; and I hereby declare the same in andby the following full, clear, and exact description thereof, referencebeing had to the accompanying drawings.

This invention relates, broadly, to devices for securing the doors ofstructures that are subjected to heavy internal pressure, such ascertain kinds of kilns, vulcanizers, air or gas receivers, orstoragechambers, and any of the other various structures in which gasesor fluids are confined or stored under pressure, temporarily orotherwise.

More particularly, the invention relates to the doors of structures inwhich material is to be treated under pressure, and which are frequentlyopened for the purpose of recharging them with the material to betreated, and which, therefore, require large doors to give ready andunobstructed access to their interiors, and fastenings for such doorsthat not only have the necessary strength, but are adapted to quicklysecure and unfasten the door.

Usually, heretofore-the fastenings for the doors of such structures haveconsisted of some form of cross-bars or levers that were caused to actupon the doors through the medium of hand-screws or wedges; but suchdevices are inconvenient, and with large doors, where many fasteningsare necessary, much time is lost in securing all of them. So, also, withsuch appliances it is impossible to secure any correspondence orinteraction between the internal pressure and the power exerted by thelocking devices hence when the internal pressure of the structure isbrought to bear upon the door the door may be found not to be closedsufficiently tight, which will necessitate the removal of the internalpressure to better secure it; or a sudden increase of the internalpressure may so loosen the door from its seat that a blow-out willoccur, and the whole process of treatment be interrupted.

The object of this invention, therefore, is, first, to furnish the doorwith fastenings that can quickly be brought into operative conditweenthe power acting upon the fastening devices and the agent exerting thepressure within the structure thatany increase of the force exerted bythe latter will. proportionately increase the former; and, fourth, tofurnish the fastening mechanism with a safety device arranged to preventthe agent that is used to create the interior pressure from acting byleakage to lose its control over or reverse the action of suchmechanism. v

The particular construction that is chosen to illustrate the principlesof the invention is a kiln or drying-chamber designed for treatinglumber by a certain drying process not necessary to elaboratehere; andthe invention consists in devices and combination of devices shown inthe accompanying drawings, in

which Figure l is a face view of a door having my ends jointed to acommon cross-head, E, and their outer ends held loosely in place byguides F. These levers have a bearing against the door at or close tothe edge thereof, and the staples G, or any equivalent devices attachedto the frame-work of the door, are constructed and arranged to receivethe outer ends of the levers and serve as their fulcra. Moving thecross-head toward the door causes all the levers to be simultaneouslyextended beyond the edge of the door and brought into engagement withthese staples, as seen particularly in Fig. 2, thereby securing thedoor, and moving the cross-head away from the door withdraws said leversfrom the staples, leaving the door free to be swung around on itshinges.

H is a piston contained in a cylinder, I, which is built in or otherwisesecured to the door, and J is the rod of the piston which passes throughthe head of the cylinder, and carries on its outer end the cross-headwhich operates the levers.

K is a steam-pipe leading from some source of steam to the outer end ofthe cylinder. It

is provided at L with a cut-off valve, and on the inside of the door atM with a check-valve which is arranged to establish communicationbetween the cylinder and the interior of the drying-chamber whenever thepressure within this chamber is greater than that within the cylinder.

N is a waste or leak pipe running from the inner end of the cylinder infront of the piston to a point outside of the door, where it has adischarge-opening at O.

P is a branch pipe connecting this wastepipe to the steam-pipe K, and isprovided with a cut-off valve, Q.

R is apetcock, whereby the cylinder is exhausted.

S is a carrying-wheel to relieve the hinges when the door is open.

The operation of the mechanism is this: After the drying chamber hasbeen filled with lumber and the door swung into its closed position, andbefore admitting steam or the other agent to be employed in the chamber,steam is let into the cylinder I, driving the piston inward and therebyextending the levers and locking the door securely in place by theaction of the levers upon the fixed staples and movable edge of thedoor. Steam or the other agent employed is then admitted to thedrying-chamber through any suitable conduit, and the drying processproceeds, the pressure in the cylinder being maintained as long as it isdesired to have the door closed. If, while the cylinderis thus filledwith steam, any steam should leak past the piston to the inner end ofthe cylinder, it is carried off by the waste-pipe, and thus preventedfrom counteracting the effect of the steam behind the piston, as itwould otherwise do. So, also, if, during the time the lumber is beingtreated, the pressure within the drying-chamber should be increased, andif for any reason the same increase of pressure is not communicated tothe piston H through the pipe leading to the locking-cylinder, thecheck-valve will open, thus putting the cylinder in communication withthe interior of the drying-chamber, and the pressure upon the pistonwill be correspondingly increased to meet and resist the additionalstrain to which the door-fastenings are subjected. If there were nochannel of communication provided between the cylin der and thedrying-chamber, such increase of the pressure in the latter mightovercome the retaining power of the fastenings and force the door open.The check-valve serves to confine the pressure within the cylinderduring the process of first closing the door, and also whenever thepressure in the main chamber is less than that in the cylinder.

To open the door, first, the steam is exhausted from the drying-chamber,then the steam is cutoff from the cylinder and its petcock opened toexhaust the steam, and then steam is carried from the main steam-pipe tothe inner end of the cylinder to force the piston outwardly and withdrawthe lever-bars; it being understood that the discharge-opening in thewaste-pipe, while sufficiently large to permit the escape of the wasteor leaking steam, is too small to permit the free escape of the livesteam, which, though escaping slightly at this opening, is still amplyactive to drive the piston outwardly and unlock the door. It will inpractice he found advisable not to provide a cock for closing thiswastepipe. If, accidentally, such a cock, if used, should be leftclosed, the accumulation of steam in front of the piston might seriouslyinterfere with the working of the apparatus by tending to equalize thepressure on both sides of the piston.

It is necessary that the leverage of the fastening-bars should be suchthat the product of it into the power applied to the piston, whichproduct represents the holding power of these bars, shall be somethinggreater than the internal pressure that the door sustains; and, as amatter of safety, it is preferred that this excess of power exerted bythe fastening mechanism should be at least one-fourth more than isrequired to hold the door locked.

It will be plain to those familiar with this kind of mechanism that itis susceptible of various modifications in construction, and I donottherefore confine myself to the exact form shown. So, too, it is notnecessary, though usually desirable, to employ the same medium ofpressure to operate the piston that is employed within thedrying-chamber; thus the piston might be operated by hydraulic or airpressure, and steam be used within the drying chamber; and it is whentwo distinct media of pressure are thus used that the checkvalveconnection is more particularly required. And, while in the specialconstruction shown in the drawings the steam or other agent used in themain chamber is to be introduced thereto through some other channel thanthe pipe which supplies the cylinder, it is plain that the main chambermight be supplied from the cylinder itself, in which case a check-valvein the passage leading from the cylinder to the chamber would not benecessary.

What is claimed as new is- 1. The combination, in a digester or othersimilar structure, of a door for closing the same, one or morelever-bars for securing the door in the closed position, and a cylinderand piston, the piston being arranged to extend and withdraw said bars,substantially as and for the purpose set forth.

2. The combination of the door, a system of lever-bars arranged radiallythereon, and

a piston and cylinder attached to the door, said piston being arrangedto extend and withdraw said bars, substantially as and for the purposeset forth.

3. The combination of the door, a system of levers arranged thereon, across-head common to said levers and a cylinder and piston, said pistonbeing arranged to operate said bars through the medium of saidcross-head, substantially as set forth.

4. In combination with the door of a digester or similar structure, barsfor holding the door in its closed position, and a locking cylinder andpiston,said piston being arranged to operate said bars, and saidcylinder communicating with the interior of the digester, for thepurpose set forth.

5. In combination with the door of a digester' or similar structure,bars for holding the door in its closed position, and a locking cylinderand piston,said piston being arranged to operate said bars, and saidcylinder com-,

